from rest_framework import serializers

from books.models import Book, FontStyle, BackgroundColor, ReadingProgress, ReadingSettings


class BookListSerializer(serializers.ModelSerializer):
    """Lightweight serializer for the library listing — no file or progress data."""

    filename = serializers.CharField(read_only=True)
    progress = serializers.SerializerMethodField()

    class Meta:
        model = Book
        fields = [
            "id",
            "title",
            "author",
            "filename",
            "cover_image",
            "created_at",
            "progress",
        ]

    def get_progress(self, obj: Book) -> float | None:
        try:
            return obj.reading_progress.current_position
        except ReadingProgress.DoesNotExist:
            return None


class BookDetailSerializer(serializers.ModelSerializer):
    """Full serializer for the reader view — includes file URL and progress."""

    filename = serializers.CharField(read_only=True)
    file_url = serializers.SerializerMethodField()
    progress = serializers.SerializerMethodField()

    class Meta:
        model = Book
        fields = [
            "id",
            "title",
            "author",
            "filename",
            "file_url",
            "cover_image",
            "created_at",
            "updated_at",
            "progress",
        ]

    def get_file_url(self, obj: Book) -> str:
        request = self.context.get("request")
        if request and obj.file:
            return request.build_absolute_uri(obj.file.url)
        return ""

    def get_progress(self, obj: Book) -> dict | None:
        try:
            rp = obj.reading_progress
            return {
                "current_position": rp.current_position,
                "last_page": rp.last_page,
            }
        except ReadingProgress.DoesNotExist:
            return None


class BookUploadSerializer(serializers.ModelSerializer):
    """Serializer for uploading a new book."""

    class Meta:
        model = Book
        fields = ["title", "author", "file", "cover_image"]
        extra_kwargs = {
            "title": {"required": True},
            "file": {"required": True},
        }

    def validate_file(self, value: object) -> object:
        import os
        if isinstance(value, type(None)):
            return value
        ext = os.path.splitext(str(getattr(value, 'name', '')))[1].lower()
        if ext not in (".epub", ".pdf"):
            raise serializers.ValidationError(
                "Only EPUB and PDF files are supported."
            )
        return value

    def create(self, validated_data: dict) -> Book:
        validated_data["user"] = self.context["request"].user
        return super().create(validated_data)


class ReadingProgressSerializer(serializers.ModelSerializer):
    class Meta:
        model = ReadingProgress
        fields = ["current_position", "last_page"]
        extra_kwargs = {
            "current_position": {"required": True, "min_value": 0.0, "max_value": 100.0},
        }

    def validate_current_position(self, value: float) -> float:
        if value < 0.0 or value > 100.0:
            raise serializers.ValidationError(
                "Position must be between 0.0 and 100.0."
            )
        return value


class ReadingSettingsSerializer(serializers.ModelSerializer):
    class Meta:
        model = ReadingSettings
        fields = ["font_size", "font_style", "background_color"]

    def validate_font_size(self, value: int) -> int:
        if value < 12 or value > 36:
            raise serializers.ValidationError("Font size must be between 12 and 36.")
        return value

    def validate_font_style(self, value: str) -> str:
        valid = [s.value for s in FontStyle]
        if value not in valid:
            raise serializers.ValidationError(
                f"Font style must be one of: {', '.join(valid)}"
            )
        return value

    def validate_background_color(self, value: str) -> str:
        valid = [c.value for c in BackgroundColor]
        if value not in valid:
            raise serializers.ValidationError(
                f"Background color must be one of: {', '.join(valid)}"
            )
        return value